In a superconducting time-reversal-symmetry-breaking Weyl semimetal, the vortex line hosts Majorana flat bands (MFBs): dispersionless zero-energy Bogoliubov-de Gennes modes spanning a finite interval of the momentum along the vortex. Modelling the Weyl semimetal as a stack of Chern insulators with varying Chern number along z lets the vortex bound states be decomposed into those of kz-resolved superconducting Chern insulators, whose topological phase diagram fixes the exact momentum boundaries of the flat bands. Tuning chemical potential or pairing strength extends the MFBs across the whole kz axis, a kz-resolved Z2 Chern-Simons invariant diagnoses them, and an attractive Hubbard interaction realises the required BCS pairing.
This paper reports the emergence of Majorana flat bands (MFBs) in the vortex line of superconducting time-reversal-symmetry-breaking Weyl semimetals. Treating a Weyl semimetal as a stack of Chern ins…